This invention relates to a photo and pressure sensitive recording medium employing photo-sensitive microcapsules and, more particularly, to a recording medium on which an image can be recorded by means of light.
A photo and pressure sensitive recording medium is known from Japanese Patent Application Laid-Open Nos. 58-17432, 58-88739, 62-143044 and so on. In the known recording medium, microcapsules each primarily containing photo-curable resin, polymerization initiator and dye precursor are carried on a planar plastic sheet such as, for example, a polyethylene terephthalate film. In use of the recording medium, microcapsules carried on the plastic sheet are first exposed to light in accordance with optical information. Subsequently, the recording medium is superimposed upon a sheet (hereinafter referred to as "developer sheet") coated with developer material which can react with the dye precursor to develop color. Pressure is then applied to the superimposed recording medium and developer sheet to effect pressure fixing. By the pressure fixing, some of the microcapsules, which are not exposed to light, are destroyed so that the contents of the destroyed microcapsules react with the developer material on the developer sheet. Thus, an image is formed on the developer sheet.
In the conventional photo and pressure sensitive recording medium, however, there is such tendency that, when the microcapsules on the recording medium are exposed to light in accordance with optical information and, subsequently, the recording medium is superimposed upon the developer sheet to perform pressure fixing, not only do the contents of the microcapsules low in mechanical strength adhere to the developer sheet, but also a layer of the microcapsules adheres to the developer sheet. The above tendency is remarkable when the surrounding air is high in temperature and high in humidify at the pressure fixing. This is because adhesion strength of resinous binder coated on the plastic film together with the microcapsules is lowered as the temperature and humidify of the surrounding air rise. On the other hand, resinous binder, which is not lowered in adhesion strength even under high temperature and high humidity, is generally firm and strong. If such resinous binder is used in the recording medium, inconvenience occurs when the unexposed microcapsules are destroyed.
The developer sheet, to which the microcapsule layer adheres, is put out of order in its surface condition, that is, the surface of the developer sheet is roughened. Thus, a beautiful and fine image output cannot be obtained. Such image is low in commodity value.